Electronic clock and control method for electronic clock

Abstract

To provide an electronic watch that can discriminate the polarity of a stepping motor without moving hands, and a method for controlling an electronic watch.SOLUTION: An electronic watch comprises: hands; a stepping motor that drives the hands; a drive circuit that drives the stepping motor; a control unit that controls the drive circuit; a current detection circuit that detects the value of current flowing in the drive circuit; and a storage unit that stores information on the polarity of a drive pulse output from the control unit to the drive circuit. When the storage unit is initialized, the control unit initializes the polarity information stored in the storage unit, outputs a polarity detection pulse in which the stepping motor does not make one step rotation to the drive circuit based on the initialized polarity information, according to output of the polarity detection pulse and based on the current value detected by the current detection circuit, executes polarity discrimination processing of discriminating whether the polarity of the stepping motor matches the polarity information, and when both do not match each other, changes the polarity information.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electronic timepiece and a method for controlling an electronic timepiece. [Background technology]

[0002] Patent Document 1 discloses an electronic timepiece that shortens the time required for hand position detection after a system reset by first moving the hands in the reverse direction and then moving them in the forward direction to detect whether the hands are at their reference positions when the system is reset, such as when installing hands or inserting a battery. Before moving the hands in the reverse direction, this electronic timepiece outputs two forward drive pulses to move the hands to align the polarity of the rotor. By outputting two forward drive pulses, the hands are driven one step if the rotor polarity is incorrect, and driven two steps if the polarity is correct, thereby aligning the rotor polarity with the drive pulse polarity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-113782 Summary of the Invention [Problem to be solved by the invention]

[0004] The electronic watch in Patent Document 1 outputs two forward rotation drive pulses to align the rotor polarity upon system reset. Therefore, if the hands are in their reference positions, the polarity alignment will cause them to shift. Therefore, the hands must be moved a certain number of steps in the reverse direction before moving in the forward direction to detect whether they have reached the reference positions, which takes time. For this reason, it has been desired to eliminate the output of drive pulses for polarity alignment, i.e., to be able to determine the rotor polarity without moving the hands. [Means for solving the problem]

[0005] The electronic timepiece disclosed herein comprises hands, a stepping motor having a coil and driving the hands, a drive circuit that drives the stepping motor, a control unit that controls the drive circuit, a current detection circuit that detects the value of the current flowing through the drive circuit, and a memory unit that stores polarity information of the drive pulse output from the control unit to the drive circuit, wherein the control unit initializes the polarity information stored in the memory unit when the memory unit is initialized, outputs a polarity detection pulse to the drive circuit based on the initialized polarity information so that the stepping motor does not rotate one step, and executes a polarity determination process that determines whether the polarity of the stepping motor matches the polarity information based on the current value detected by the current detection circuit in response to the output of the polarity detection pulse, and changes the polarity information if they do not match.

[0006] The electronic timepiece disclosed herein comprises hands, a stepping motor having a coil and driving the hands, a drive circuit that drives the stepping motor, a control unit that controls the drive circuit, a current detection circuit that detects the value of the current flowing through the drive circuit, and a memory unit that stores polarity information of the drive pulse output from the control unit to the drive circuit, wherein the control unit outputs a polarity detection pulse to the drive circuit that prevents the stepping motor from rotating one step based on the polarity information stored in the memory unit, the current detection circuit detects the current value while outputting the polarity detection pulse, the control unit measures the elapsed time from the start of output of the polarity detection pulse, and if the elapsed time until it detects that the current value has exceeded a predetermined value is within the predetermined time, determines that the polarity of the stepping motor matches the polarity information, and if the elapsed time exceeds the predetermined time, determines that the polarity of the stepping motor does not match the polarity information, and changes the polarity information if they do not match.

[0007] The control method for an electronic timepiece disclosed herein is a control method for an electronic timepiece that includes hands, a stepping motor having a coil and driving the hands, a drive circuit that drives the stepping motor, a current detection circuit that detects the value of the current flowing through the drive circuit, and a memory unit that stores polarity information of the drive pulse output to the drive circuit, and is characterized in that when the memory unit is initialized, the polarity information stored in the memory unit is initialized, a polarity detection pulse that prevents the stepping motor from rotating one step is output to the drive circuit based on the initialized polarity information, and a polarity determination process is performed to determine whether the polarity of the stepping motor matches the polarity information based on the current value detected by the current detection circuit in response to the output of the polarity detection pulse, and if they do not match, the polarity information is changed.

[0008] The electronic timepiece control method disclosed herein is a control method for an electronic timepiece that includes hands, a stepping motor having a coil and driving the hands, a drive circuit that drives the stepping motor, a current detection circuit that detects the value of the current flowing through the drive circuit, and a memory unit that stores polarity information of the drive pulse to be output to the drive circuit, and is characterized in that it outputs a polarity detection pulse to the drive circuit that prevents the stepping motor from rotating one step based on the polarity information stored in the memory unit, detects the current value while the polarity detection pulse is being output by the current detection circuit, measures the elapsed time from the start of output of the polarity detection pulse, and determines that the polarity of the stepping motor and the polarity information match if the elapsed time exceeds the predetermined time, determines that the polarity of the stepping motor and the polarity information do not match, and changes the polarity information if they do not match. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view showing an electronic timepiece according to a first embodiment. [Figure 2] 1 is a circuit diagram showing the circuit configuration of an electronic timepiece according to a first embodiment. [Figure 3] FIG. 2 is a diagram showing the configuration of a first motor of the electronic timepiece according to the first embodiment. [Figure 4] FIG. 1 is a diagram showing the configuration of an IC of an electronic timepiece according to a first embodiment. [Figure 5] FIG. 2 is a circuit diagram showing the configuration of a first motor control circuit of the first embodiment. [Figure 6] 4 is a flowchart illustrating a polarity detection process according to the first embodiment. [Figure 7] 5A and 5B are diagrams showing waveforms of currents flowing through the drive circuit when polarities match in the first embodiment. [Figure 8] 5A and 5B are diagrams showing waveforms of currents flowing through the drive circuit when the polarities of the first embodiment are mismatched. [Figure 9] 10 is a flowchart illustrating a polarity detection process according to the second embodiment. [Figure 10] 10 is a diagram showing a waveform of a current flowing through a drive circuit when polarities match in the second embodiment. FIG. [Figure 11] 10 is a diagram showing a waveform of a current flowing through a drive circuit when the polarities of the second embodiment are mismatched. FIG. [Figure 12] 10 is a flowchart illustrating a polarity detection process according to a third embodiment. [Figure 13] 10 is a flowchart illustrating another example of the polarity detection process according to the third embodiment. [Figure 14] FIG. 10 is a circuit diagram showing the circuit configuration of an electronic timepiece according to a fourth embodiment. [Figure 15] 10 is a flowchart illustrating a control process according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] [First embodiment] An electronic timepiece 1 according to a first embodiment will now be described with reference to the drawings. Figure 1 is a front view of the electronic timepiece 1. The electronic timepiece 1 is a chronograph timepiece equipped with a stopwatch function and the like. As shown in FIG. 1, the electronic timepiece 1 includes a circular dial 2, a second hand 3, a minute hand 4, an hour hand 5, a crown 6, a button A 7, and a button B 8.

[0011] [Circuit configuration of electronic clock] FIG. 2 is a diagram showing the circuit configuration of the electronic timepiece 1. As shown in FIG. 2, the electronic timepiece 1 includes a movement 10 that drives a second hand 3, a minute hand 4, and an hour hand 5, which are hands.

[0012] The movement 10 comprises a quartz oscillator 11 which is a signal source, a battery 12 which is a power source, switches SW1 to SW3, a first motor 13, a second motor 14, and an IC 20 for the timepiece. Switch SW1 is turned on and off in conjunction with the pulling out of crown 6 shown in Figure 1. Switch SW2 is turned on and off in conjunction with the operation of button A 7. Switch SW3 is turned on and off in conjunction with the operation of button B 8. The first motor 13 is a stepping motor that drives the second hand 3, and the second motor 14 is a stepping motor that drives the minute hand 4 and the hour hand 5. Also, IC is an abbreviation for Integrated Circuit.

[0013] The IC20 has connection terminals OSC1 and OSC2 to which the crystal oscillator 11 is connected, input / output terminals G1 to G3 to which switches SW1 to SW3 are connected, power supply terminals VDD and VSS to which the battery 12 is connected, output terminals O1 and O2 to which the first motor 13 is connected, and output terminals O3 and O4 to which the second motor 14 is connected. In this embodiment, the positive electrode of the battery 12 is connected to the high potential side power supply terminal VDD, the negative electrode is connected to the low potential side power supply terminal VSS, and the low potential side power supply terminal VSS is set to the reference potential.

[0014] The battery 12 is a primary battery or a secondary battery. In the case of a secondary battery, it is charged by a power generation device such as a solar cell (not shown).

[0015] 3 is a diagram showing the configuration of the first motor 13. Note that the second motor 14 has the same configuration as the first motor 13, although a description thereof will be omitted. As shown in Fig. 3, the first motor 13 includes a stator 131, a coil 130, and a rotor 133. Both ends of the coil 130 are electrically connected to output terminals O1 and O2 of the IC 20. The rotor 133 is a magnet that is magnetized with two poles in the radial direction. Therefore, the first motor 13 is a two-pole single-phase stepping motor used in electronic watches, and is driven by a drive current supplied from the output terminals O1 and O2 of the IC 20.

[0016] For example, when a drive current is passed through coil 130 from output terminal O1 to output terminal O2, a counterclockwise magnetic field is generated in FIG. 3. This magnetic field polarizes stator 131, causing it to repel rotor 133 and rotate rotor 133 by 180°, which is a unit amount. Once rotor 133 has rotated 180°, a drive current is passed from output terminal O2 to output terminal O1. This generates a clockwise magnetic field in FIG. 3. This magnetic field polarizes stator 131 in the opposite direction to the previous one, causing it to repel rotor 133 and rotate rotor 133 another 180°. Rotor 133 continues to rotate by repeating this operation. In this way, switching the direction of the drive current by switching output terminals O1 and O2 that supply the drive current each time rotor 133 rotates by a unit amount is equivalent to switching the polarity of the drive current. The IC20 of this embodiment rotates the rotor 133 by a desired amount by repeatedly switching between two polarities: a first polarity that causes a drive current to flow from output terminal O1 to output terminal O2, and a second polarity that causes a drive current to flow from output terminal O2 to output terminal O1. In this specification, the orientation of the rotor 133, which can be expressed as an angle between 0 and 360°, is referred to as the "rotation angle," and the cumulative angle of rotation when a unit amount of rotation is repeated multiple times is referred to as the "rotation amount." Similarly, the second motor 14 is driven by a driving current supplied to the output terminals O3 and O4 of the IC 20.

[0017] [IC circuit configuration] FIG. 4 is a diagram showing the configuration of the IC 20. As shown in Figure 4, the IC 20 includes an oscillator circuit 21, a frequency divider circuit 22, a CPU 23 (the control unit of the electronic timepiece 1), a ROM 24, a RAM 25, an input circuit 26, a BUS 27, a first motor control circuit 30A, and a second motor control circuit 30B. The first motor control circuit 30A and the second motor control circuit 30B are examples of motor control circuits. CPU stands for Central Processing Unit, ROM stands for Read Only Memory, and RAM stands for Random Access Memory.

[0018] The oscillator circuit 21 causes the crystal oscillator 11, which is the reference signal source shown in FIG. 2, to oscillate at a high frequency, and outputs an oscillation signal of a predetermined frequency (32768 Hz) generated by this high-frequency oscillation to the frequency divider circuit 22. The frequency divider circuit 22 divides the output of the oscillator circuit 21 and supplies a timing signal and a 1 Hz reference signal to the CPU 23 . The ROM 24 stores various programs executed by the CPU 23. In this embodiment, the ROM 24 stores programs for realizing a timekeeping function, a stopwatch function, etc., as well as a program for realizing a polarity detection function for detecting the polarity of the stepping motor after resetting. The CPU 23 executes the programs stored in the ROM 24 to realize the above-mentioned functions. That is, the CPU 23 realizes a timekeeping function that counts the reference signal supplied from the frequency divider circuit 22 to measure the current time and the elapsed time during stopwatch operation, a drive control function that controls the drive of the stepping motor to move the hands according to the measured time, and a polarity detection function that detects the polarity of the stepping motor.

[0019] The input circuit 26 outputs the states of the input / output terminals G1 to G3 to the BUS 27. The BUS 27 is used for data transfer between the CPU 23, the input circuit 26, the first motor control circuit 30A, and the second motor control circuit 30B. The first motor control circuit 30A and the second motor control circuit 30B supply a predetermined drive current to the coils 130 of the first motor 13 and the second motor 14 in response to drive pulses input from the CPU 23 via the BUS 27. At this time, the CPU 23 outputs drive pulses to the first motor control circuit 30A and the second motor control circuit 30B according to polarity information stored in the RAM 25. For this reason, the RAM 25 is a storage unit that stores polarity information, i.e., the first polarity or the second polarity, of the drive pulses output to the first motor control circuit 30A and the second motor control circuit 30B. The polarity information stored in the RAM 25 alternates between the first polarity and the second polarity each time the CPU 23 outputs a drive pulse. Furthermore, when the RAM 25 is initialized by a system reset or the like, the CPU 23 also initializes the polarity information stored in the RAM 25. In this embodiment, when the RAM 25 is initialized, the CPU 23 stores the first polarity in the RAM 25 as the initial value of the polarity information.

[0020] [Motor control circuit configuration] The first motor control circuit 30A controls the first motor 13 so that the second hand 3 can move in both forward and reverse directions, that is, both clockwise and counterclockwise. Therefore, the first motor control circuit 30A only needs to be capable of driving and controlling the first motor 13 in both forward and reverse directions. Similarly, the second motor control circuit 30B controls the second motor 14 so that the minute hand 4 and the hour hand 5 can move in both forward and reverse directions.

[0021] 5 is a circuit diagram showing the configuration of the first motor control circuit 30 A. The configuration of the second motor control circuit 30 B is similar to that of the first motor control circuit 30 A, and therefore a description thereof will be omitted. The first motor control circuit 30A includes a decoder 31, a driver 50, and a current detection circuit 60. The decoder 31 outputs a control signal to the driver 50 based on the drive pulse output from the CPU 23. That is, the drive pulse of the first polarity or the second polarity output from the CPU 23 is input to the decoder 31 via the BUS 27. The decoder 31 outputs gate signals P1, P2, N1, N2, N3, and N4 as control signals to the driver 50 depending on the polarity of the input drive pulse. That is, when a drive pulse of the first polarity is input, the decoder 31 outputs a control signal set to cause a drive current to flow from the output terminal O1 to the output terminal O2 of the coil 130, and when a drive pulse of the second polarity is input, the decoder 31 outputs a control signal set to cause a drive current to flow from the output terminal O2 to the output terminal O1 of the coil 130. Therefore, the CPU 23, the BUS 27, and the decoder 31 form a driver control unit that controls the driver 50.

[0022] The driver 50 is a drive circuit that supplies current to the coil 130 of the first motor 13 to drive the stepping motor. The driver 50 includes two P-channel transistors 52 and 53, four N-channel transistors 54, 55, 56, and 57, and two detection resistors 58 and 59. Each of the transistors 52 to 57 is controlled by a control signal output from the decoder 31, and supplies current I to the coil 130 of the first motor 13 in both forward and reverse directions.

[0023] Current detection circuit 60 includes first reference voltage generation circuit 62, second reference voltage generation circuit 63, comparators 641, 642, 651, 652, and composite gates 68, 69. Composite gate 68 is a single element having a function equivalent to a combination of AND circuits 661, 662 and an OR circuit 680. Composite gate 69 is a single element having a function equivalent to a combination of AND circuits 671, 672 and an OR circuit 690.

[0024] The comparators 641 and 642 compare the voltage generated across the coil 130 with the voltage of the first reference voltage generating circuit 62, respectively. The AND circuit 661 receives an inverted version of the drive polarity signal PL output from the decoder 31, and the AND circuit 662 receives the drive polarity signal PL as is, so that one of the outputs of the comparators 641, 642 selected by the drive polarity signal PL is output as the detection signal DT1. The comparators 651 and 652 compare the voltage generated across the coil 130 with the voltage of the second reference voltage generating circuit 63, respectively. The drive polarity signal PL is inverted and input to the AND circuit 671, and the drive polarity signal PL is input directly to the AND circuit 672, so that one of the outputs of the comparators 651, 652 selected by the drive polarity signal PL is output as the detection signal DT2.

[0025] The first reference voltage generating circuit 62 selectively generates a voltage corresponding to the lower limit target current value Imin or a voltage corresponding to the polarity-discriminating current value Ith, which is a current value smaller than the lower limit target current value Imin. When polarity discrimination is performed, a selection signal for selecting the polarity discrimination current value Ith is input from the CPU 23 to the first reference voltage generating circuit 62 via the BUS 27, and the first reference voltage generating circuit 62 outputs a potential corresponding to the voltage generated across the coil 130 when the current I flowing through the coil 130 is the polarity discrimination current value Ith. Furthermore, as will be described later, when the motor is driven in fast forward mode, a selection signal for selecting the lower limit target current value Imin is input from the CPU 23 to the first reference voltage generating circuit 62 via the BUS 27, and the first reference voltage generating circuit 62 outputs a potential corresponding to the voltage generated across the coil 130 when the current I flowing through the coil 130 is the lower limit target current value Imin. Therefore, when the motor is driven, if the current I flowing through the coil 130 is equal to or greater than the lower-limit target current value Imin, the voltage generated across the coil 130 is equal to or greater than the output voltage of the first reference voltage generation circuit 62, causing the detection signal DT1 to go high. On the other hand, if the current I is below the lower-limit target current value Imin, the detection signal DT1 goes low. Therefore, the first reference voltage generation circuit 62, comparators 641 and 642, and composite gate 68 of the current detection circuit 60 are configured to be able to detect when the current I flowing through the coil 130 changes from a value greater than the lower-limit target current value Imin to a value smaller than it. Similarly, when polarity is being determined, if the current I flowing through the coil 130 is equal to or greater than the polarity-determining current value Ith, the voltage generated across the coil 130 is equal to or greater than the output voltage of the first reference voltage generating circuit 62, causing the detection signal DT1 to go high. On the other hand, if the current I is lower than the polarity-determining current value Ith, the detection signal DT1 goes low. Therefore, the first reference voltage generating circuit 62, comparators 641 and 642, and composite gate 68 of the current detection circuit 60 are configured to detect a change in the current I flowing through the coil 130 from a value smaller than the polarity-determining current value Ith to a value larger than the polarity-determining current value Ith by the first reference voltage generating circuit 62 selecting the polarity-determining current value Ith.

[0026] The second reference voltage generating circuit 63 generates a voltage corresponding to the upper limit target current value Imax. Therefore, the detection signal DT2 of the current detecting circuit 60 becomes H level when the current I flowing through the coil 130 exceeds the upper limit target current value Imax, and becomes L level when the current I is equal to or less than the upper limit target current value Imax. Therefore, the second reference voltage generating circuit 63, comparators 651 and 652, and composite gate 69 of the current detecting circuit 60 are configured to be able to detect when the current I flowing through the coil 130 changes from a value smaller than the upper limit target current value Imax to a value larger than the upper limit target current value Imax.

[0027] [Polarity detection processing] Next, the polarity detection process during a system reset of the electronic timepiece 1 will be explained with reference to Figure 6. A system reset is executed when the operator operates the crown 6, button A 7, or button B 8, when there is an input to the system reset terminal exposed by opening the back cover, when a battery is inserted, or when certain other conditions are met.

[0028] When the system reset is executed, the CPU 23 executes step S11, starts up the system, and initializes internal data such as polarity information stored in the RAM 25. Therefore, the information stored in the RAM 25 becomes the first polarity, which is the initial value. Next, the CPU 23 executes step S12 and starts outputting a polarity detection pulse of the initialized first polarity. The polarity detection pulse is a pulse that prevents the rotor 133 from rotating one step, e.g., a pulse output that prevents the rotor 133 from rotating one step, e.g., a pulse output that prevents the rotor 133 from rotating one step, by setting the pulse width, i.e., the voltage application time, based on the relationship between the resistance value and electromotive force of the coil 130. For example, for a stepping motor with a coil 130 resistance of 2 kΩ, the current polarity of the stepping motor can be determined by setting the polarity detection pulse width to 300 μsec and the polarity discrimination current value Ith to 0.16 mA. For a stepping motor with a coil 130 resistance of 500 Ω, the polarity can be determined by setting the polarity detection pulse width to 100 μsec and the polarity discrimination current value Ith to 1.6 mA.

[0029] Next, the CPU 23 executes step S13, and waits for a preset current change time. The current change time is set according to the pulse width of the polarity detection pulse, i.e., the polarity detection time. That is, the current change time is slightly shorter than the polarity detection time. For example, if the polarity detection time is 300 μsec, the current change time is set to approximately 280 μsec, and if the polarity detection time is 100 μsec, the current change time is set to approximately 90 μsec.

[0030] When the current change time has elapsed since the start of output of the polarity detection pulse, the CPU 23 executes step S14 to detect the current flowing through the driver 50, which is the drive circuit, i.e., the current I flowing through the coil 130. Specifically, a voltage equivalent to the polarity-discriminating current value Ith is selected as the voltage generated by the first reference voltage generating circuit 62, and it is detected whether the value of the current I flowing through the coil 130 exceeds the polarity-discriminating current value Ith. Fig. 7 is a diagram showing the waveform of current I when the polarity of rotor 133 and the polarity of the polarity detection pulse match, and Fig. 8 is a diagram showing the waveform of current I when the polarity of rotor 133 and the polarity of the drive pulse do not match. As described above, since CPU 23 outputs a polarity detection pulse of a first polarity, decoder 31 controls each of transistors 52 to 57 so that output terminal O1 is connected to power supply terminal VDD and output terminal O2 is connected to power supply terminal VSS, i.e., ground. 7 and 8, V_O1 is the voltage value at output terminal O1, and V_O2 is the voltage value at output terminal O2. As shown in FIG. 7, when a polarity detection pulse is output from CPU 23 and the voltage V_O1 at output terminal O1 changes from L (VSS) to H (VDD), a current I flows through coil 130. Here, as shown in FIG. 7, if the polarity of rotor 133 matches the polarity of the polarity detection pulse, rotor 133 repels, and an induced current is generated quickly. Therefore, at current detection timing Td after the current change time has elapsed, current I exceeds polarity-discriminating current value Ith, and detection signal DT1 becomes H level. On the other hand, as shown in FIG. 8, if the polarities do not match, rotor 133 performs an attracting operation, and an induced current is generated slowly. Therefore, at current detection timing Td, current I becomes less than polarity-discriminating current value Ith, and detection signal DT1 becomes L level. Therefore, the CPU 23 outputs a polarity detection pulse to apply a voltage to the output terminal O1, and checks the level of the detection signal DT1 to see if the current I detected at a predetermined current detection timing Td exceeds the polarity discrimination current value Ith, which is a predetermined value, thereby determining the polarity of the rotor 133.

[0031] After executing the current detection process in step S14, the CPU 23 executes step S15, and stops outputting the polarity detection pulse when the polarity detection time has elapsed since the start of outputting the polarity detection pulse. Next, the CPU 23 executes step S16, and determines whether or not the detected current value exceeds the polarity determination current value Ith based on the level of the detection signal DT1 when the current is detected in step S14. If the CPU 23 determines YES in step S16, it determines in step S17 that the position of the rotor 133, i.e., the polarity, matches the IC control polarity, i.e., the polarity information stored in the RAM 25, and ends the polarity detection process. Here, since the polarity detection pulse is the first polarity as described above, the current polarity of the rotor 133 is the first polarity, and the step motor can be driven by next outputting a drive pulse of the first polarity.

[0032] On the other hand, if the determination in step S16 is NO, the CPU 23 determines in step S18 that the position of the rotor 133, i.e., the polarity, does not match the IC control polarity, i.e., the polarity information stored in the RAM 25. Therefore, the CPU 23 executes step S19 to change the polarity information stored in the RAM 25. That is, since the initial value of the polarity information stored in the RAM 25 is the first polarity, the CPU 23 changes the polarity information in the RAM 25 to the second polarity, and ends the polarity detection process.

[0033] By performing the above polarity detection process, the polarity information for motor control stored in RAM 25, i.e., the IC control polarity, matches the current polarity of the stepping motor rotor 133. Therefore, the stepping motor can be reliably driven by outputting drive pulses from CPU 23 based on the polarity information stored in RAM 25. That is, during normal hand movement, the CPU 23 outputs drive pulses with a constant pulse width to the first motor control circuit 30A and the second motor control circuit 30B, and moves each hand one step at a predetermined time interval. Furthermore, when fast-forwarding the hands, such as when executing a stopwatch function or correcting the hand position, the CPU 23 performs current-controlled driving to move the hands. In current-controlled driving to fast-forward the hands, the CPU 23 sets a lower-limit target current value Imin and an upper-limit target current value Imax in the first reference voltage generating circuit 62 and the second reference voltage generating circuit 63, respectively, and controls them to an ON state in which a drive current is supplied to the coil 130. After that, when the current value detected by the current detecting circuit 60 exceeds the upper-limit target current value Imax, the CPU 23 switches to an OFF state in which no drive current is supplied, and when the current value detected by the current detecting circuit 60 falls below the lower-limit target current value Imin, the CPU 23 switches to an ON state in which a drive current is supplied. Then, when a preset polarity-switching condition, such as the duration of the ON state or the OFF state, is met, the CPU 23 controls by switching the polarity of the drive current.

[0034] [Effects of the first embodiment] According to the first embodiment described above, the following effects can be obtained. By outputting a polarity detection pulse after a system reset, the polarity of the rotor 133 can be detected without driving the step motor. For example, when assembling the electronic watch 1, if the hands are aligned to the reference position and then installed, and the battery is then installed and started up, the polarity can be adjusted without moving the hands, which shortens the processing time required to align the hands to the reference position compared to the conventional method of adjusting the polarity by moving the hands from the reference position.

[0035] Furthermore, because the current value is determined to have exceeded the predetermined polarity-discriminating current value Ith at the current detection timing Td, i.e., immediately before the end of the polarity detection pulse output, the pulse width of the polarity detection pulse can be fixed in advance. This allows the polarity detection process to be performed in the same amount of time regardless of whether the polarities match or mismatch. Furthermore, since the process of detecting and determining the current value only needs to be performed once while the polarity detection pulse is being output, control is simplified and power consumption can be reduced compared to when the process of detecting and determining the current value is performed multiple times while the polarity detection pulse is being output.

[0036] The polarity discrimination current value Ith, which is a predetermined value in the polarity discrimination process, is set smaller than the lower limit target current value Imin of the target current value in the drive process. Therefore, the pulse width of the polarity detection pulse can be made smaller than when the polarity discrimination current value Ith is set to the same value as the lower limit target current value Imin, thereby reducing power consumption.

[0037] [Second embodiment] Next, an electronic timepiece according to a second embodiment will be described. In the second embodiment, the configuration of the electronic timepiece 1 is the same as in the first embodiment, but the polarity detection processing method differs from that in the first embodiment. Therefore, the polarity detection method according to the second embodiment will be described with reference to the flowchart in FIG.

[0038] When the system reset is executed, the CPU 23 executes step S21, starts up the system, and initializes internal data such as polarity information stored in the RAM 25. Therefore, the information stored in the RAM 25 becomes the first polarity, which is the initial value. Next, the CPU 23 executes step S22, outputs a polarity detection pulse to the driver 50, and starts applying a voltage to the coil .

[0039] Next, the CPU 23 executes step S23 to detect the current flowing through the coil 130. Specifically, the CPU 23 selects a voltage equivalent to the polarity-discriminating current value Ith as the voltage generated by the first reference voltage generating circuit 62, and detects whether the current I flowing through the coil 130 exceeds the polarity-discriminating current value Ith. After detecting the current in step S23, the CPU 23 executes step S24 to determine whether the detected current I exceeds the polarity determination current value Ith. If the determination in step S24 is NO, the CPU 23 periodically executes steps S23 and S24. On the other hand, if the answer to step S24 is YES, the CPU 23 executes step S25, stops outputting the polarity detection pulse, and stops applying the voltage.

[0040] Next, the CPU 23 executes step S26 to determine whether the time from the start of voltage application until the current I flowing through the coil 130 reaches the designated current value, that is, the polarity determination current value Ith, is within a predetermined time. Here, Figure 10 is a diagram showing the waveform of current I when the polarity of rotor 133 and the polarity of the polarity detection pulse match, and Figure 11 is a diagram showing the waveform of current I when the polarity of rotor 133 and the polarity of the drive pulse do not match. As shown in Fig. 10, when the polarities match, rotor 133 repels, causing an induced current to be generated quickly. On the other hand, as shown in Fig. 11, when the polarities do not match, rotor 133 performs an attracting action, causing an induced current to be generated slowly. For this reason, CPU 23 periodically performs current detection at T1, T2, ..., and checks whether the number of current detections at the time when the detected current I reaches polarity-discriminating current value Ith is equal to or less than a preset judgment value, thereby making it possible to determine whether the time from voltage application to reaching the designated current value is within a predetermined time. In this embodiment, the predetermined time is set to the time it takes for eight current detections to be performed after the start of voltage application, and the CPU 23 determines YES in step S26 if the current I has reached the polarity-discriminating current value Ith by T8, which is the eighth current detection timing, and determines NO if it has reached nine or more times. In the case of FIG. 10, the current I is equal to or greater than the polarity-discriminating current value Ith at T7, which is the seventh current detection timing, so the CPU 23 determines YES in step S26. On the other hand, in the case of FIG. 11, the current I is equal to or greater than the polarity-discriminating current value Ith at T11, which is the eleventh current detection timing, so the CPU 23 determines NO in step S26.

[0041] If the CPU 23 judges YES in step S26, it executes step S27, similar to step S17 in the first embodiment, and determines that the position, i.e., polarity, of the rotor 133 matches the IC control polarity, i.e., the polarity information stored in RAM 25, and terminates the polarity detection process. Furthermore, if the CPU 23 judges NO in step S26, it executes step S28, similar to steps S18 and S19 in the first embodiment, to determine that the position, i.e., polarity, of the rotor 133 does not match the IC control polarity, i.e., the polarity information stored in RAM 25, and executes step S29 to change the polarity information stored in RAM 25.

[0042] By performing the polarity detection process described above, even in the second embodiment, the polarity information for motor control stored in RAM 25, i.e., the IC control polarity, matches the current polarity state of the rotor of the stepping motor. Therefore, the stepping motor can be reliably driven by outputting drive pulses from CPU 23 based on the polarity information stored in RAM 25. Note that the operation of the hands during normal hand movement and fast-forward hand movement is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0043] [Effects of the second embodiment] The second embodiment described above can also achieve the same effects as the first embodiment. Furthermore, since the current value is detected periodically while the polarity detection pulse is being output and the current detection process is terminated when it is detected that the detected current I has exceeded a predetermined polarity-discriminating current value Ith, polarity detection can be performed in a short time, particularly when the polarities match. Also, since the output of the polarity detection pulse is stopped when it is detected that the current I has exceeded the polarity-discriminating current value Ith, the output time of the polarity detection pulse can be shortened, particularly when the polarities match, and power consumption can be reduced.

[0044] In the second embodiment, the time elapsed since the start of output of the polarity detection pulse may be measured, and if the elapsed time exceeds a certain time while the detected current value does not exceed the polarity determination current value Ith, the output of the polarity detection pulse may be stopped, and it may be determined that the polarity of the rotor 133 does not match the polarity information stored in the RAM 25. For example, if the determination in step S24 is NO and the number of current detections, which indicates the elapsed time since the start of output of the polarity detection pulse, reaches a predetermined number, for example, 20 times, it may be determined that the polarity detection process has timed out, and steps S28 and S29 may be executed. By adding such a time-over judgment, the output of the polarity detection pulse will be stopped after a certain time has elapsed even if the detected current I does not exceed the polarity discrimination current value Ith, thereby preventing an increase in power consumption due to the continued output of the polarity detection pulse.

[0045] [Third embodiment] Next, an electronic timepiece according to a third embodiment will be described. The electronic timepiece of the third embodiment differs from that of the first embodiment in the specifications of the IC 20. That is, the IC 20 of the third embodiment cannot directly change the polarity of the drive pulses managed by the IC 20, i.e., the polarity information stored in the RAM 25, but changes it by outputting the drive pulses. A polarity detection method according to the third embodiment for an electronic timepiece using an IC 20 with such specifications will be described with reference to the flowchart of FIG. 12, in the third embodiment, steps S11 to S18 are the same as those in the first embodiment, and therefore a description thereof will be omitted. After processing step S18, the CPU 23 executes step S30 and outputs one drive pulse. This drive pulse is a fixed pulse with a preset pulse width, and is a pulse that can drive the stepping motor one step when the polarity of the rotor 133 matches the polarity information in the RAM 25. In step S30, since the rotor position and the IC control polarity do not match, the rotor 133 does not rotate even when one drive pulse is output, and the polarity information stored in RAM 25 is changed. Therefore, the polarity information in RAM 25 can be changed to match the polarity of the rotor 133. After the polarity detection process shown in Figure 12 is completed, the polarity of the rotor 133 can be matched with the polarity information stored in RAM 25, so that when the motor is subsequently driven, a drive pulse with matching polarity can be output, ensuring reliable driving of the stepping motor.

[0046] In the third embodiment, the same polarity determination method as in the second embodiment may be adopted. The polarity detection process in this case is shown in the flowchart of Fig. 13. As shown in Fig. 13, steps S21 to S28 are the same processes as in the second embodiment, and therefore their explanation will be omitted. After processing step S28, CPU 23 executes step S30, outputs one drive pulse, and changes the polarity information in RAM 25 to match the polarity of rotor 133. Furthermore, a time-over determination may be added to the processing in Fig. 13.

[0047] [Effects of the third embodiment] According to the third embodiment, even in an electronic watch using an IC20 in which polarity information cannot be changed directly, the polarity of the rotor 133 can be detected and a drive pulse output only if it does not match the polarity information in RAM25, thereby changing the polarity information to match without rotating the rotor 133.

[0048] [Fourth embodiment] An electronic timepiece 1B according to a fourth embodiment and its polarity detection process will be described with reference to FIGS. As shown in Figure 14, the electronic timepiece 1B is the electronic timepiece 1 of the first embodiment with the addition of a hand position detection mechanism. That is, the movement 10B of the electronic timepiece 1B is equipped with a light-emitting element 71 and a light-receiving element 72 as a hand position detection mechanism that detects whether the hands are in a reference position. Specifically, it is equipped with a light-emitting element 71 and a light-receiving element 72 arranged on either side of the train wheel that drives the second hand 3, and a light-emitting element 71 and a light-receiving element 72 arranged on either side of the train wheel that drives the minute hand 4 and the hour hand 5. Furthermore, the IC20B of the electronic timepiece 1B has the same configuration as the IC20 of the first embodiment, except for the inclusion of terminals O5 to O8 to which the light-emitting element 71 and the light-receiving element 72 are connected, and therefore a description thereof will be omitted.

[0049] The train wheel that drives the second hand 3 has a detection hole that is located between the light-emitting element 71 and the light-receiving element 72 when the second hand 3 is at the 0 second position, which is the reference position, and the detection light output from the light-emitting element 71 when the second hand 3 is at the reference position is received by the light-receiving element 72. This makes it possible to detect that the second hand 3 is at the reference position. Similarly, when the minute hand 4 and the hour hand 5 are at the 0:00 position, which is the reference position, the detection light from the light-emitting element 71 is received by the light-receiving element 72, making it possible to detect that they are at the reference position. The electronic timepiece 1B also includes a power generation device such as a solar panel, and the battery 12 is a secondary battery that can be charged with the power generated by the power generation device.

[0050] Next, the control process in the electronic timepiece 1B will be described with reference to the flowchart in FIG. The CPU 23 of the IC 20B executes step S41 and periodically detects the battery voltage while the hands are moving, such as during normal operation to display the time with the hands or during stopwatch operation. Next, the CPU 23 executes step S42 and determines whether the voltage detected in step S41 has dropped to a preset power save transition voltage or less. If the determination in step S42 is NO, the CPU 23 repeats steps S41 and S42. If the CPU 23 determines YES in step S42, it executes step S43, moves the hands to their reference positions, and transitions to power save mode. In power save mode, the CPU 23 continues to measure time, but the first motor 13 and the second motor 14 are not driven, and the movement of the hands is maintained stopped. Therefore, the second hand 3, minute hand 4, and hour hand 5 are stopped at their reference positions.

[0051] After the CPU 23 has entered the power save mode in step S43, it executes step S44 and periodically detects the battery voltage. Next, the CPU 23 executes step S45 to determine whether the voltage detected in step S44 has returned to a preset power save release voltage or higher. The power save release voltage is a voltage higher than the power save transition voltage, and the CPU 23 determines YES in step S45 when the battery 12 is charged by the power generation device and the battery voltage rises. If the CPU 23 determines YES in step S45, it executes step S46 and cancels the power save mode. After canceling the power save mode, the CPU 23 quickly moves the second hand 3, minute hand 4, and hour hand 5 to positions indicating the time they were measuring, and returns to normal operation, and then returns to step S41 to continue control. On the other hand, if the CPU 23 determines NO in step S45, it executes step S47 and determines whether the voltage detected in step S44 has dropped below the IC operable voltage, which is a voltage even lower than the power save transition voltage.

[0052] If the CPU 23 determines NO in step S47, the CPU 23 returns to step S44 and continues the control. On the other hand, if the determination in step S47 is YES, the CPU 23 executes step S48 and stops the operation of the IC 20B, which causes the internal data stored in the RAM 25, such as polarity information, to be lost.

[0053] Thereafter, in step S49, if the battery voltage is less than the preset system startup voltage, that is, while the determination in step S49 is NO, the IC operation stop state continues. The system startup voltage is a voltage value higher than the IC operation voltage, and is preferably set to a voltage value higher than the power save transition voltage so that the system does not transition to power save mode immediately after startup. When the battery 12 is charged by the power generation device and the battery voltage becomes equal to or higher than the system startup voltage, and the determination in step S49 is YES, the CPU 23 executes polarity detection processing in step S50. The polarity detection processing is the same as the polarity detection processing in any of the first to third embodiments, and therefore a description thereof will be omitted. That is, if the specifications of the IC 20 allow the polarity information in the RAM 25 to be directly changed, the polarity detection processing same as that in Fig. 6 or Fig. 9 is executed. Furthermore, if the specifications of the IC 20 require the output of a drive pulse to change the polarity information in the RAM 25, the polarity detection processing same as that in Fig. 12 or Fig. 13 is executed.

[0054] After executing the polarity detection process in step S50, CPU 23 executes step S51 and performs reference position detection process using light-emitting element 71 and light-receiving element 72. At this time, in the polarity detection process in step S50, rotor 133 does not rotate, so the positions of the hands are maintained at the reference positions to which they were moved in step S43. Therefore, in step S51, it can be detected that each hand is located at the reference position in the first reference position detection operation. After detecting the reference position in step S51, the CPU 23 executes step S52 and begins normal operation. When normal operation begins, the hands also begin moving, but because the operation of the IC 20 has stopped and the internal data has been lost, the time indicated by the hands is likely to differ from the current time. In this case, the user performs an operation to adjust the hands. For example, if the electronic watch 1B has the function of receiving a standard radio wave or a satellite signal to set the time, a forced reception operation can be performed. Also, if the electronic watch 1B manually sets the time using the crown 6, button A 7, or button B 8, the time can be set by manually moving the hands.

[0055] [Effects of the fourth embodiment] According to the electronic timepiece 1B of this embodiment, the polarity detection process of step S50 is executed when system startup begins after the operation of the IC 20B has stopped and polarity information has been lost, so the polarity of the rotor 133 can be detected without moving the rotor 133. As a result, the polarity detection process can be executed without moving the hands that were moved to the reference position when the power save mode was entered, and the reference position detection process of step S51 can then be executed with the hands in the reference position. This means that the reference position detection process can be completed in a short time, there is no need to move the hands to align them to the reference position, and power consumption can be reduced. Furthermore, when the remaining charge of the secondary battery 12, i.e., the battery voltage, falls below a predetermined threshold, which is the power save mode transition voltage, the hands are moved to the reference position and the drive is stopped, thereby suppressing a drop in the voltage of the battery 12.

[0056] [Other embodiments] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. For example, although the polarity-discriminating current value Ith in each of the above embodiments is the same value, the polarity-discriminating current value Ith in the first and third embodiments may be different from the polarity-discriminating current value Ith in the second and fourth embodiments. The storage unit for storing the polarity information is not limited to the RAM 25, but may be an internal storage unit provided in the CPU 23.

[0057] In the fourth embodiment, when the watch entered power save mode, the second hand 3, minute hand 4, and hour hand 5 were all moved to their reference positions. However, the minute hand 4 and hour hand 5 may be moved to their reference positions, and the second hand 3 may be moved to a mode position indicating that the watch has entered power save mode, for example, the 45-second position, and stopped there. Furthermore, if the electronic timepiece 1B is equipped with a date wheel, the date wheel may be moved to a reference position and stopped. Wristwatches often do not have a hand position detection mechanism for the date wheel, and so when adjusting the date wheel to the reference position, the date wheel must be moved to the reference position manually. Therefore, if the date wheel is moved to the reference position in advance in power save mode, there is no need to move the date wheel when adjusting the reference position, and the reference position adjustment process can be completed in a short time, reducing power consumption.

[0058] Furthermore, the polarity detection process is not limited to being performed when RAM 25 is initialized, but may be performed periodically while the hands are moving, or, for example, in an electronic watch having a built-in acceleration sensor, it may be performed when it is detected that the electronic watch has been dropped, that is, when the rotor 133 has rotated and there is a possibility that the polarity has changed.

[0059] Summary of this disclosure The electronic timepiece disclosed herein comprises hands, a stepping motor having a coil and driving the hands, a drive circuit that drives the stepping motor, a control unit that controls the drive circuit, a current detection circuit that detects the value of the current flowing through the drive circuit, and a memory unit that stores polarity information of the drive pulse output from the control unit to the drive circuit, wherein the control unit initializes the polarity information stored in the memory unit when the memory unit is initialized, outputs a polarity detection pulse to the drive circuit based on the initialized polarity information so that the stepping motor does not rotate one step, and executes a polarity determination process that determines whether the polarity of the stepping motor matches the polarity information based on the current value detected by the current detection circuit in response to the output of the polarity detection pulse, and changes the polarity information if they do not match. According to the electronic timepiece of the present disclosure, a polarity detection pulse that does not cause the stepping motor to rotate one step based on the initialized polarity information, i.e., a pulse with a narrower pulse width than the drive pulse, is output, so that it is possible to determine whether the polarity of the stepping motor matches the initialized polarity information without driving the stepping motor, and if it does not match, change the polarity information. In other words, since the polarity can be adjusted while maintaining the position of the hands during initialization, when adjusting the reference position, there is no need to output drive pulses in the forward and reverse directions to move the hands, as in the past, and the processing time required to adjust the hands to the reference position can be shortened.

[0060] In the electronic watch disclosed herein, it is preferable that the control unit determines whether the current value exceeds a predetermined value based on the output of the polarity detection pulse, and if the current value exceeds the predetermined value, determines that the polarity of the stepping motor matches the polarity information. According to the electronic timepiece of the present disclosure, since it is only necessary to determine whether the current value exceeds a predetermined value immediately before the end of output of the polarity detection pulse, the pulse width of the polarity detection pulse can be fixed in advance. Therefore, the polarity detection process can be performed in the same amount of time regardless of whether the polarities match or mismatch. Furthermore, since the process of detecting and determining the current value only needs to be performed once while the polarity detection pulse is being output, power consumption can be reduced compared to when the process of detecting and determining the current value is performed multiple times while the polarity detection pulse is being output.

[0061] In the electronic watch disclosed herein, it is preferable that the current detection circuit detects the current value while the polarity detection pulse is being output, and the control unit measures the elapsed time from the start of output of the polarity detection pulse, and determines that the polarity of the stepping motor matches the polarity information if the elapsed time until it detects that the current value has exceeded a predetermined value is within the predetermined time. According to the electronic watch disclosed herein, the current value is detected while the polarity detection pulse is being output, and the polarity is determined based on the elapsed time until it is detected that the current value has exceeded a predetermined value, so that processing can be completed in a short time, especially when the polarities match.

[0062] In the electronic timepiece of this disclosure, it is preferable that the control unit stops outputting the polarity detection pulse when it detects that the current value has exceeded a predetermined value. According to the electronic watch disclosed herein, the output of the polarity detection pulse can be stopped as soon as it is detected that the current value has exceeded a predetermined value, and therefore, the output time of the polarity detection pulse can be shortened, particularly when the polarities match, thereby reducing power consumption.

[0063] In the electronic watch disclosed herein, it is preferable that the control unit measures the elapsed time from the start of outputting the polarity detection pulse, and when the elapsed time exceeds a certain period of time while the current value does not exceed a predetermined value, stops outputting the polarity detection pulse and determines that the polarity and the polarity information do not match. According to the electronic watch disclosed herein, even if the detected current value does not exceed a predetermined value, the output of the polarity detection pulse is stopped after a certain period of time has elapsed, thereby preventing an increase in power consumption due to the continued output of the polarity detection pulse.

[0064] In the electronic watch disclosed herein, the drive circuit is controlled to an on state in which a drive current is supplied to the coil, and an off state in which the drive current is not supplied, and the control unit, in the drive process of the hands, compares the current value detected by the current detection circuit with a target current value and controls the drive circuit to the on state or the off state depending on the result of the comparison, and it is preferable that the predetermined value in the polarity discrimination process is smaller than the target current value in the drive process. According to the electronic watch disclosed herein, the predetermined value in the polarity discrimination process is smaller than the target current value in the drive process, so the pulse width of the polarity detection pulse can be made smaller than when the predetermined value is set to the same value as the target current value, thereby reducing power consumption.

[0065] In the electronic watch disclosed herein, when the control unit determines that the polarity of the stepping motor does not match the polarity information, it is preferable that the control unit changes the polarity information based on the initialized polarity information by outputting a drive pulse to the drive circuit that drives the stepping motor by one step if the polarity of the stepping motor matches the polarity information. According to the electronic timepiece of the present disclosure, if it is determined that the polarity of the stepping motor does not match the polarity information, a drive pulse with a mismatched polarity is output, so the stepping motor is not driven and only the polarity information stored in the memory unit can be changed. Therefore, the electronic timepiece can be applied to electronic timepieces in which the polarity information cannot be directly changed due to IC specifications.

[0066] In the electronic watch disclosed herein, it is preferable that the watch is equipped with a secondary battery and a power generation device capable of charging the secondary battery, and that the control unit moves at least one hand to a reference position and stops driving the moved hand when the remaining charge of the secondary battery falls below a predetermined threshold. According to the electronic timepiece of the present disclosure, when the remaining charge of a secondary battery charged by a power generation device such as a solar panel, i.e., the battery voltage, falls below a predetermined threshold, the hands are moved to their reference positions and operation is stopped, thereby preventing a voltage drop in the secondary battery. Also, if the memory unit is initialized due to a further drop in battery voltage, and then the secondary battery voltage rises due to charging by the power generation device and the system starts up, if the hands are in their reference positions, they can be aligned to their reference positions without moving them.

[0067] In the electronic timepiece disclosed herein, it is preferable that the electronic timepiece is provided with a hand position detection mechanism that detects whether at least one of the hands is in the reference position, and that when the memory unit is initialized, the control unit executes the hand position detection process using the hand position detection mechanism after the polarity determination process. According to the electronic watch disclosed herein, when polarity determination processing is performed while the hands are in the reference position, the hands do not move from the reference position, so when the hand position detection processing is performed using the hand position detection mechanism, the hands can be detected in the shortest time possible, thereby minimizing the hand position detection processing time and reducing power consumption accordingly.

[0068] The electronic timepiece disclosed herein comprises hands, a stepping motor having a coil and driving the hands, a drive circuit that drives the stepping motor, a control unit that controls the drive circuit, a current detection circuit that detects the value of the current flowing through the drive circuit, and a memory unit that stores polarity information of the drive pulse output from the control unit to the drive circuit, wherein the control unit outputs a polarity detection pulse to the drive circuit that prevents the stepping motor from rotating one step based on the polarity information stored in the memory unit, the current detection circuit detects the current value while outputting the polarity detection pulse, the control unit measures the elapsed time from the start of output of the polarity detection pulse, and if the elapsed time until it detects that the current value has exceeded a predetermined value is within the predetermined time, determines that the polarity of the stepping motor matches the polarity information, and if the elapsed time exceeds the predetermined time, determines that the polarity of the stepping motor does not match the polarity information, and changes the polarity information if they do not match. According to the electronic timepiece of the present disclosure, a polarity detection pulse that does not cause the stepping motor to rotate one step based on the polarity information stored in the memory unit, i.e., a pulse with a narrower pulse width than the drive pulse, is output, so that it is possible to determine whether the polarity of the stepping motor matches the stored polarity information without driving the stepping motor, and if it does not match, change the polarity information. In other words, because the polarity can be adjusted while maintaining the position of the hands, when adjusting the reference position, there is no need to output drive pulses in the forward and reverse directions to move the hands, as in the past, and the processing time required to adjust the reference position can be shortened. Furthermore, the current value is detected while the polarity detection pulse is being output, and the polarity is determined based on the elapsed time until it is detected that the current value has exceeded a predetermined value. Therefore, processing can be completed in a short time, especially when the polarities match.

[0069] The control method for an electronic timepiece disclosed herein is a control method for an electronic timepiece that includes hands, a stepping motor having a coil and driving the hands, a drive circuit that drives the stepping motor, a current detection circuit that detects the value of the current flowing through the drive circuit, and a memory unit that stores polarity information of the drive pulse output to the drive circuit, and is characterized in that when the memory unit is initialized, the polarity information stored in the memory unit is initialized, a polarity detection pulse that prevents the stepping motor from rotating one step is output to the drive circuit based on the initialized polarity information, and a polarity determination process is performed to determine whether the polarity of the stepping motor matches the polarity information based on the current value detected by the current detection circuit in response to the output of the polarity detection pulse, and if they do not match, the polarity information is changed. According to the control method for an electronic timepiece disclosed herein, a polarity detection pulse that does not cause the stepping motor to rotate one step based on initialized polarity information, i.e., a pulse with a narrower pulse width than the drive pulse, is output, so that it is possible to determine whether the polarity of the stepping motor matches the initialized polarity information without driving the stepping motor, and if it does not match, change the polarity information. In other words, since the polarity can be adjusted while maintaining the position of the hands during initialization, when adjusting the reference position, there is no need to output drive pulses in the forward and reverse directions to move the hands, as in the past, and the processing time required to adjust the reference position can be shortened.

[0070] The electronic timepiece control method disclosed herein is a control method for an electronic timepiece that includes hands, a stepping motor having a coil and driving the hands, a drive circuit that drives the stepping motor, a current detection circuit that detects the value of the current flowing through the drive circuit, and a memory unit that stores polarity information of the drive pulse to be output to the drive circuit, and is characterized in that it outputs a polarity detection pulse to the drive circuit that prevents the stepping motor from rotating one step based on the polarity information stored in the memory unit, detects the current value while the polarity detection pulse is being output by the current detection circuit, measures the elapsed time from the start of output of the polarity detection pulse, and determines that the polarity of the stepping motor and the polarity information match if the elapsed time exceeds the predetermined time, determines that the polarity of the stepping motor and the polarity information do not match, and changes the polarity information if they do not match. According to the electronic timepiece control method disclosed herein, a polarity detection pulse (i.e., a pulse with a narrower pulse width than the drive pulse) is output based on the polarity information stored in the memory unit, preventing the stepping motor from rotating one step. Therefore, without driving the stepping motor, it is possible to determine whether the stepping motor's polarity matches the stored polarity information, and if it does not match, change the polarity information. In other words, since the polarity can be adjusted while maintaining the hand position, when adjusting the reference position, there is no need to output drive pulses in both forward and reverse directions to move the hands, as in the past, and the processing time required to adjust the reference position can be shortened. Furthermore, since the current value is detected while the polarity detection pulse is being output, and the polarity is determined based on the elapsed time until it is detected that the current value exceeds a predetermined value, processing can be completed in a short time, especially when the polarity matches. [Explanation of symbols]

[0071] 1...electronic clock, 1B...electronic clock, 3...second hand, 4...minute hand, 5...hour hand, 10...movement, 10B...movement, 11...quartz crystal oscillator, 12...battery, 13...first motor, 14...second motor, 20...IC, 20B...IC, 23...CPU, 24...ROM, 25...RAM, 30A...first motor control circuit, 30B...second motor control circuit, 31...decoder, 50...driver, 60...current detection circuit, 62...first reference voltage generation circuit, 63...second reference voltage generation circuit, 130...coil, 131...stator, 133...rotor.

Claims

1. Guidelines and a stepping motor having a coil and driving the pointer; a drive circuit for driving the stepping motor; a control unit that controls the drive circuit; a current detection circuit for detecting a value of a current flowing through the drive circuit; a storage unit that stores polarity information of a drive pulse output from the control unit to the drive circuit, The control unit When the storage unit is initialized, the polarity information stored in the storage unit is initialized; outputting a polarity detection pulse to the driving circuit based on the initialized polarity information, which prevents the stepping motor from rotating by one step; executes a polarity determination process for determining whether or not the polarity of the stepping motor matches the polarity information based on the current value detected by the current detection circuit in response to the output of the polarity detection pulse; If there is a mismatch, change the polarity information. An electronic watch characterized by:

2. 2. The electronic timepiece according to claim 1, The control unit determines whether the current value exceeds a predetermined value based on the output of the polarity detection pulse, and if the current value exceeds the predetermined value, determines that the polarity of the stepping motor matches the polarity information. An electronic watch characterized by:

3. 2. The electronic timepiece according to claim 1, the current detection circuit detects the current value while the polarity detection pulse is being output; The control unit measures the elapsed time from the start of output of the polarity detection pulse, and determines that the polarity of the stepping motor matches the polarity information if the elapsed time from the start of output of the polarity detection pulse to the point at which it detects that the current value has exceeded a predetermined value is within a predetermined time. An electronic watch characterized by:

4. 4. The electronic timepiece according to claim 3, The control unit stops outputting the polarity detection pulse when it detects that the current value has exceeded a predetermined value. An electronic watch characterized by:

5. 5. The electronic timepiece according to claim 3 or 4, The control unit measures the elapsed time from the start of output of the polarity detection pulse, and when the elapsed time exceeds a certain time while the current value does not exceed a predetermined value, stops output of the polarity detection pulse and determines that the polarity and the polarity information do not match. An electronic watch characterized by:

6. 6. The electronic timepiece according to claim 1, the drive circuit is controlled to an ON state in which a drive current is supplied to the coil, and an OFF state in which the drive current is not supplied, the control unit, in the process of driving the hands, compares the current value detected by the current detection circuit with a target current value, and controls the drive circuit to the on state or the off state according to a result of the comparison; The predetermined value in the polarity determination process is smaller than the target current value in the drive process. An electronic watch characterized by:

7. 7. The electronic timepiece according to claim 1, When the control unit determines that the polarity of the stepping motor does not match the polarity information, the control unit outputs a drive pulse to the drive circuit to drive the stepping motor by one step when the polarity of the stepping motor matches the polarity information, based on the initialized polarity information, and changes the polarity information. An electronic watch characterized by:

8. 8. The electronic timepiece according to claim 1, A secondary battery; a power generation device capable of charging the secondary battery; When the remaining charge of the secondary battery falls below a predetermined threshold, the control unit moves at least one hand to a reference position and stops driving the moved hand. An electronic watch characterized by:

9. 9. The electronic timepiece according to claim 8, a hand position detection mechanism for detecting when the at least one pointer is at the reference position; When the storage unit is initialized, the control unit executes the polarity determination process and then executes the hand position detection process using the hand position detection mechanism. An electronic watch characterized by:

10. Guidelines and a stepping motor having a coil and driving the pointer; a drive circuit for driving the stepping motor; a control unit that controls the drive circuit; a current detection circuit for detecting a value of a current flowing through the drive circuit; a storage unit that stores polarity information of a drive pulse output from the control unit to the drive circuit, The control unit a polarity detection pulse that prevents the stepping motor from rotating by one step is output to the drive circuit based on the polarity information stored in the storage unit; the current detection circuit detects the current value while the polarity detection pulse is being output; The control unit measuring the time that has elapsed since the start of output of the polarity detection pulse, and determining that the polarity of the stepping motor matches the polarity information if the time that has elapsed until it is detected that the current value has exceeded a predetermined value is within the predetermined time, and determining that the polarity of the stepping motor does not match the polarity information if the time that has elapsed exceeds the predetermined time; If there is a mismatch, change the polarity information. An electronic watch characterized by:

11. A control method for an electronic timepiece comprising hands, a stepping motor having a coil and driving the hands, a drive circuit driving the stepping motor, a current detection circuit detecting the value of a current flowing through the drive circuit, and a memory unit storing polarity information of a drive pulse output to the drive circuit, comprising: When the storage unit is initialized, the polarity information stored in the storage unit is initialized; outputting a polarity detection pulse to the driving circuit based on the initialized polarity information, which prevents the stepping motor from rotating by one step; executes a polarity determination process for determining whether or not the polarity of the stepping motor matches the polarity information based on the current value detected by the current detection circuit in response to the output of the polarity detection pulse; If there is a mismatch, change the polarity information.

10. A method for controlling an electronic watch.

12. A control method for an electronic timepiece comprising hands, a stepping motor having a coil and driving the hands, a drive circuit driving the stepping motor, a current detection circuit detecting the value of a current flowing through the drive circuit, and a memory unit storing polarity information of a drive pulse output to the drive circuit, comprising: a polarity detection pulse that prevents the stepping motor from rotating by one step is output to the drive circuit based on the polarity information stored in the storage unit; The current detection circuit detects the current value while the polarity detection pulse is being output; measuring the time that has elapsed since the start of output of the polarity detection pulse, and determining that the polarity of the stepping motor matches the polarity information if the time that has elapsed until it is detected that the current value has exceeded a predetermined value is within the predetermined time, and determining that the polarity of the stepping motor does not match the polarity information if the time that has elapsed exceeds the predetermined time; If there is a mismatch, change the polarity information.

10. A method for controlling an electronic watch.

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